“Each computer run would last 1,000-2,000 hours, and, because we didn’t really trust a program that ran so long, we ran it twice, and it verified that the results matched. I’m not sure I ever was present when a run finished.”

Skimming Michael Betancourt’s history of MCMC [discussed yesterday in this space] made me think: my first computer job was as a nighttime computer operator on the old Rice (R1) Computer, where I was one of several students who ran Monte Carlo programs written by (the very good) chemistry prof Dr. Zevi Salsburg and his grad students. As I recall, each computer run would last 1,000-2,000 hours, and, because we didn’t really trust a program that ran so long, we ran it twice, and it verified that the results matched. I’m not sure I ever was present when a run finished.

>Here are a few pictures of the Rice Computer, along with the USAEC Bessel Function Generator. Wikipedia has more, as does Google.

Thinking a bit more, I was told we were running it twice ’cause the hardware might make an error (or so I recall), but perhaps we were simply running two chains on a room-sized single processor with 32K words.

https://ricehistorycorner.com/2012/01/31/new-info-on-the-rice-computers/ is a bit more on the Rice Computer and Salsburg, and https://archive.li/opI1Y is perhaps the definitive online documentation about the machine. It indicates that (apparently) some or much of Salsburg’s work on the Rice Computer was done on the bare machine, which means no Genie programming language; I don’t know if it meant no assembler. The computer’s ability to do dynamic memory allocation using tagged memory and codewords is the reason I always heard Salsburg wanted this machine; the IBM machines of the time ran out of memory and didn’t, apparently, have the ability to reclaim unused memory.

And it’s still my favorite computer! Real superscripts and subscripts, thanks to the Friden Flexowriter and the Genie language, and flashing neon lamps everywhere, which made an impressive sight at night, especially if you turned the room lights off.

Oooh, I love this sort of thing. I guess that’s a sign that I’m getting old. 2018 is in the future, after all.